In the field of vehicle drivetrain components, a transfer case is an apparatus that distributes driving power to more than one driven axle of the vehicle. A typical transfer case receives driving power from the transmission of the vehicle and transfers that power to a primary output shaft. The primary output shaft is driven generally constantly, for example, during operation of the vehicle in a two-wheel drive mode, and a secondary output shaft that is driven selectively using a clutch, for example, during operation of the vehicle in a four-wheel drive mode. In addition, two-speed transfer cases provide gear reduction to allow operation in a high range, which is typically a 1:1 drive ratio, or a low range, such as a 2:1 drive ratio.
Oil may be provided to the clutch, for example, to cool the clutch that engages the secondary output shaft. However, when the clutch is not engaged and the secondary output shaft is not driven, a continued supply of oil can create drag or friction (e.g., due to shearing of the oil between plates of the clutch) on the primary output shaft, which can reduce efficiency of the vehicle. It would, therefore, be advantageous to provide a transfer case in which oil is selectively provided to the clutch when needed.